Vehicles driven by internal combustion engines generally employ intake system sensors including, but not limited to, a throttle position sensor (TPS), a mass airflow (MAF) sensor and a manifold absolute pressure (MAP) sensor. An engine control system implements an electronic throttle control (ETC) system that regulates engine torque output based on a throttle position signal, a MAF signal and a MAP signal. The engine control system can also regulate engine torque output using spark advance/retard, cam phasing and/or regulating fuel supply to the cylinders.
Throttle body deposits commonly occur in internal combustion engines during operation. Understanding and compensating for throttle body deposits is challenging. Statistical build variations in the ETC system components can alter the relationship between throttle position and airflow as well.
ETC systems can adapt to airflow variations resulting from throttle body deposits, throttle sensor variation, mass airflow meter variation, and manufacturing tolerances. ETC systems often slowly adapt or learn to compensate for airflow variations. The throttle position within a coked throttle body is adjusted to allow for an increase in airflow that compensates for less flow due to coking. The addition of greater airflow prevents drivability issues such as idle roll and stalls.
When a controller is reflashed or swapped, the learned values of airflow correction compensating for the coking are lost and drivability issues can result. The speed of learning compensating values can be an impediment to improving driving performance and stable idle speed. Balancing the speed of learning with accuracy of control can often be a difficult task.